Many of the brighter stars are given names which are known as Bayer designations. These designations, which were introduced by Johann Bayer in his star atlas Uranometria (named after Urania) in 1603, consist of a Greek letter followed by the genitive (in Latin) of the name of the constellation in which the star lies. See List of constellations for a list of constellations and the genitive forms of their names. .

The Messier objects are a set of astronomical objects catalogued by Charles Messier in his catalogue of Nebulae and Star Clusters first published in 1774. The original motivation behind the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets. He therefore compiled a list of these objects.
The first edition covered 45 objects numbered M1 to M45. The total list consists of 110 objects, ranging from M1 to M110. The final catalogue was published in 1781 and printed in the Connaissance des Temps in 1784. Many of these objects are still known by their Messier number.

A constellation is any one of the 88 areas into which the sky - or the celestial sphere - is divided. The term is also often used less formally to denote a group of stars visibly related to each other in a particular configuration or pattern.
Some well-known constellations contain striking and familiar patterns of bright stars. Examples are Ursa Major (containing the Big Dipper), Orion (containing a figure of a hunter), Leo (containing bright stars outlining the form of a lion) and Scorpius (a scorpion) . Other constellations do not encompass any discernible star patterns, and contain only faint stars..

The New General Catalogue (NGC) is the best-known catalogue of deep sky objects in amateur astronomy. It contains nearly 8,000 objects, known as the NGC objects. The NGC is one of the largest comprehensive catalogues, as it includes all types of deep sky objects (not specialised to just galaxies for instance)

Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. Each star is assigned a number and the Latin genitive of the constellation it lies in (see List of constellations for a list of constellations and the genitive forms of their names).
The numbers were originally assigned in order of increasing right ascension within each constellation, but due to the effects of precession they are now slightly out of order in some places. This method of designating stars first appeared in a preliminary version of John Flamsteed's Historia coelestis Britannica which was published by Edmond Halley and Isaac Newton in 1712 without Flamsteed's approval. The final version of Flamsteed's catalogue published in 1725 after his death omitted any number designations altogether.

The Virgo Cluster is a cluster of galaxies at a distance of approximately 59 ± 4 Mly (18.0 ± 1.2 Mpc) away in the constellation Virgo. Comprising approximately 2000 member galaxies, the cluster forms the heart of the larger Local Supercluster, of which the Local Group is an outlying member. It is estimated that its mass is 1.2×1015 M☉ out to 8 degrees of the cluster's center or a radius of about 2.2 Mpc.

The Index Catalogue (IC) —also known as the Index Catalogue of Nebulae, the Index Catalogue of Nebulae and Clusters of Stars, IC I, or IC II— is a catalogue of galaxies, nebulae and star clusters that serves as a supplement to the New General Catalogue. It was first published in 1895, and has been expanded to list more than 5,000 objects, known as the IC objects.

A binary star is a stellar system consisting of two stars orbiting around their center of mass. For each star, the other is its companion star. Recent research suggests that a large percentage of stars are part of systems with at least two stars. Binary star systems are very important in astrophysics, because observing their mutual orbits allows their mass to be determined. The masses of many single stars can then be determined by extrapolations made from the observation of binaries.
Thanks - Mcdonalds

The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 of the brightest stars visible from the northern hemisphere.
The catalogue was first published between 1918 and 1924. It was compiled by Annie Jump Cannon and co-workers at Harvard College Observatory under the supervision of Edward C. Pickering, and was named in honour of Henry Draper, whose widow donated the money required to finance it.
Stars contained in the catalogue are of medium magnitude, down to about 9m (about 50 times dimmer than the faintest stars visible with the naked eye). This makes them average-looking in amateur telescopes, and bright stars for professional instruments. The catalogue covers the whole sky and is notable as the first large-scale attempt to catalogue spectral types of stars.

The Quasar are very powerful astronomical objets that radiate thousands of a galaxie energy from a supermassive black hole swallowing lots of matter. Is thinking that a Quasar is actually a galaxie center.

The Hipparcos catalogue was compiled from the data gathered by the European Space Agency's astrometric satellite Hipparcos, which was operational from 1989 to 1993. This catalogue contains more than 118,000 stars.

First published in 1930 as the Yale Catalog of Bright Stars, this catalog contained information on all stars in the Sky brighter than visual magnitude 6.5 in the Harvard Revised Photometry Catalogue. The list was revised in 1983 with the publication of a supplement that listed additional stars down to magnitude 7.1. The catalog detailed each star's coordinates, proper motions, photometric data, spectral types, and other useful information (source : www.wikipedia.com)

First published in 2014 stars brighter than visual magnitude 6.5 in the Harvard Revised Photometry Catalogue. with the publication of a supplement that listed additional stars down to magnitude 7.1. The catalog detailed with spectral types, and other (source : www.wikipedia.com) useful information

Alnitak is pronounced ALL-nit-ahk. Alnitak (Zeta Orionis, 50 Ori) is a triple star system at the eastern end of Orion's belt, and is 736 light years from the Earth. It has 100,000 times the luminosity of the sun. The primary (Alnitak A) is itself a close binary, comprising Alnitak Aa (a blue supergiant of spectral and luminosity type O9.7 Ibe, with an absolute magnitude of -5.25 and an apparent magnitude of 2.0) and Alnitak Ab (a blue dwarf of spectral and luminosity type O9V, with an absolute magnitude of about -3.0 and an apparent magnitude of about 4, discovered in 1998 [2]). Aa is estimated as being up to 28 times as massive as the sun, and to have a diameter 20 times greater.[3] It is the brightest star of class O in the night sky. Alnitak B is a 4th magnitude B-type star which orbits Alnitak A every 1500 years. A fourth star, 9th magnitude Alnitak C, has not been confirmed to be part of the Aa-Ab-B group, and may simply lie along the line of sight.
The Alnitak system is bathed in the nebulosity of IC 434. Source: Wikipedia - More information